Low-temperature noncrystallizing ddt-alkylated naphthalene insecticide



Patented Sept. 7, 1948 I LOW-TEMPERATURE NONCRYSTALLIZIN G DDT-ALKYLATED NAPHTHALENE IN- SECTICIDE Elmer E. Fleck, Silver Spring, and Robert K. Preston, Cumberland, Md.: dedicated to the free use oi. the People in the United States territory of the No Drawing. Application June 22. 1945, Serial No. 601,054

1 Claim. (Cl. 167-30) I,

(Granted under the act of March 3, 1883, as

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, it patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

We hereby dedicate the invention herein described to the free use of the people in the territory of the United States to take effect on the granting of a patent to us.

This invention relates to insecticides, and more particularly to technical grade DDT, and has among its objects the improvement of the solubility of DDT in petroleum hydrocarbon oils, such as kerosene, at low temperatures. Other objects will be apparent from the description of the invention.

One of the generally accepted methods of applying DDT, 1-trichloro-2,2-bis(p-chlorophenylethane, consists in spraying a 5 per cent solution of the insecticide in kerosene, this method being possible when the temperature of the spray is maintained at about 70 F. When such a solution, however, is stored at low temperatures particularly subzero temperatures, the greater portion of the DDT separates as crystals from the solution. Subsequent handling of this solution frequently results in the pouring off of the supernatant solution without the taking of the necessary precautions to insure complete solution. As a consequence, a solution is applied which contains much less insecticide, with a resulting greatly reduced insecticidal action being obtained.

The solubility of technical grade DDT in kerosene meeting Federal specification VV-K-211a,

April 9, 1941, is about 9 g. of DDT per 100 g..0f

.kerosene at 85 F. (29 0.), andabout 2 g. per

100 g. of kerosene at F. (29 C.). It is apparent, therefore, that this low solubility of DDT at subzero temperatures becomes a serious problem when'drums of the 5 per cent solution are kept in unheated winter storage.

We have found that certain auxiliary solvents which are better solvents for DDT than is kerosene, such as substantially pure alkylated naphthalenes, and distillation petroleum hydrocarbon fractions having boiling points between about from 400 F. to 700 F. and rich in alkylated naphthalenes, including the monoand polyalkyl-ated naphthalenes' like monomethyl and dimethyl naphthalene, when added to a DDT-kerosene mixture exert unexpected action on the mixture when the latter is subjected to low temperatures, particularly subzero temperatures, the result being that the DDT does not crystallize from the amended April 30, 1928; 370 0. G. 757) 2 solution. The solubility of DDT, when dissolved in the mixture of kerosene and auxiliary solvent, has apparently been alteren by the auxiliary solvent, and a result, which is not expected by the additive solubility of the DDT in each of the respective solvents, is obtained.

In Table I, following, the solubility of DDT in parts per hundred parts of solvent in various solvents at 86 F. (30 C.) is indicated, all parts being by weight.

In Table II, also following, there are indicated solutions containing 5 parts of DDT per 100 parts of a mixture of kerosene and an auxiliary solvent, said mixture comprising 95 to 80 parts of kerosene mixed with 5 to 20 parts of auxiliary solvent. The table further indicates the proportions of auxiliary solvent mixed, in percentages, with the kerosene to yield 100 parts of mixed keroseneauxiliary solvent. Underneath these percentages are shown lists of numerals which indicate the number of days at-which the DDT-kerosene-auxiliary solvent solution was held at 20 F. before crystallization of the DUI occurred. All parts Tame: I

Solubility of DDT in various solvents at Solubility of Solvent DDT in g./ 100 g; solvent Xylene 64 Monnmetliyl naphthalene 63 Petroleum distillation fraction (Velsicol AR-) (B. P. 4505l5 F.) 53 Petroleum distillation fraction (Velsicol Ali-) (B.

P. 480-55() F.) 49 Petzo leum distillation fraction (APS-NO) (B. P. 580 4 7 l Petroleum distillation fraction (APS-202) (B. P.

550710 F. 45 Heavy Aromatic Naphtha Solvent ()3. P. over 400 F.) 48 Petroleum distillation fraction (Solvent 54413) (B. P.

504-640 F. 45 Petroleum distil tion fraction (Solvent 5440) (B. P.

392- F. 39 Petroleum distillation fraction (Solvesso #1) (B. P.

210-276 F.) n 62 Petroleum distllla n fraction (Solvesso #2) (B. P.

27035l 49,5 Petroleum distillation fraction (Solvesso #3) (B. P.

347-408 F.) 40 Diisopmpyl benzene 22 Methylethylketone. 100 Refined Kerosene .4. 5 Kerosene (Fed. S c. VV-K-211a, April 9, 1941). 9 Monoamyl napht alene. 33 Acetone 73 Toluene l: m

Tenn 11 Crystallization of nor at 40 F. from a solution containing \DDT, kerosene, and an auxiliary solvent 5 a. technical DDT per 100 9. mixed solvent No. of days at -2o I". a

solution of DDT, kerosane, and auxiliary solvent was held belore crystallization of DDT occurred Auxiliary Solvent Percentage of auxiliary solvent in solution Xylene 2 3 3 8 Monometbyl naphthalene 7 20 27 NO Petroleum distillation fraction (Velsicol AR. 50) (B. P. 4505l5 F.) 4 5 17 NC Petroleum distillationlraction (Velsicol AR 60) (B. P. 480550 F. 5 7 17 NC Petroleum distillation fraction (APB-200) (B. P. 580760 F. 4 32 NC NC Petroleum distillation i'raction (APS-202) (B. P. 550710 F.) 2 10 15 NC Heavy Aromatic N aphthe Solvent (B. P.

over 400 F. 6 6 23 NC Petroleum distillation fraction (Solvent 54413) (B. P. 504-640 F. 6 '10 21 NC Petroleum distillation fraction (Solvent 5440) (B. P. 392530 F'.) 6 6 l3 l3 Petroleum distillation fraction (Solvesso #1) (B. P. 2l0276 If.) l l 2 2 Petroleum distillation 'iraction (Solvesso B. P. 270-s51,r. 2 2 2 2 Petroleum distillation fraction (Solvesso #3) (B. P. 347408 F.) 6 6 6 6 Diisopropyl benzene 3 3 3 3 Methylethylketone 2 2 Nors.-NC=N crystallization for minimum period of 3 weeks.

I No determination made.

As may be noted from the above tables, the unexpected action of the auxiliary solvent is well exhibited in the following comparison: Xylene dissolves 64 g, of DDT per 100 g. of solvent at 86 F. (30 C.), and 20 percent of this solvent added to the percent kerosene-DDT solution to yield 100 g. of mixed kerosene and xylene deposited crystals of the DDT in 8 days at 20 F. Monomethyl naphthalene dissolves 63 g. of DDT per 100 g. of this solvent, and its solubility of DDT is therefore substantially identical to that of xylene in this respect. However, when but 10 percent of this compound was added to the 5 percent DDT-kerosene solution, to yield 100 g. of mixed preferably predominately aromatic in character and boiling within the range of about from 400 to 700 F., have been found to be the most effective in this respect. 'One commercial product of this type contains distillation fractions which boil between about 450 and 500 F., and contains upwards of 70 percent monoand dimethyl naphthalenes, the remaining hydrocarbons being verions higher-boiling alkanes, alkenes. and aromatics. A. second product contains fractions which .boil between about 500 and 550 F. and contains upwards of 70 percent polyalkylated naphth-alenes. A third product of this type known as heavy aromatic naphtha solvent, boiling higher than 400 F. and containing, largely, substituted naphthalenes and mono-nuclear aromatics, dissolves 48 g. of DDT per g. of solvent at 30 C. As shown in Table II. when 15 percent, by weight, of this solvent was added to the DDT-kerosene to yield 100 g. of mixed kerosene solvent, the resulting mixture held 5 percent of DUI in solution for 23 days at 20 F.

These alkylated naphthalene hydrocarbonfractions also have the advantage of a high flash point which does not increase the fire hazard of the kerosene solution, as would solvents such as acetone, benzene, toluene, and so forth.

The mixture of kerosene and alkylated naphthalenes also has the advantage over alkylated naphthalene hydrocarbon fractions alone, because these fractions themselves deposit crystalline material at -20 F. The'mixture of the two solvents is likewise cheaper than the auxiliary solvent alone.

Many modifications may be made in the preparation of these DDT-kerosene-auxiliary solvent solutions. Thus, we have found that to hold 5 percent DDT in solution, the preferred amount of auxiliary solvent containing alkylated naphthalenes is about 15 percent, but this can be varied within the limits of about from 5 to 20 percent, depending upon the content of alkylated naphthalenes in the solvent and on the temperature at which freedom from crystal formation is desired. Likewise, the addition of alkylated naphthalene solvents to kerosene isnot limited to 5 percent DDT solutions, but may be varied to contain about from 3 to 10 percent DDT.

Having thus described our invention, we claim:

An insecticidal composition which will remain free from crystal formation of DDT at all tem peratures between about 20 F. and F. comprising a solution of about from 95 to 80 parts, by weight, of a kerosene mixture of DDT and about from 5 to 20 parts, by weight, of substantially pure alkylated naphthalenes, said kerosene mixture containing about from 3 to 10 percent DDT.

ELMER. E. FLECK. ROBERT K. PRESTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,700 Muller Dec. 4, 1945 2,349,434 Hyman May 23, 1944 OTHER REFERENCES Jour. Econ, Entom., vol. 3, No. 1, page 127, by Madden et al., and pages 136 and 137, by Wells.

Ind. and Eng. Chem, Feb. 1946, pages 177 and 178, byFleck etal. 

